A typical circuit for implementation in semiconductor technology may require a plurality of different reference voltages to be applied at appropriate places for proper operation thereof. As an example, the input buffer circuit shown in FIG. 1 may require a reference voltage V.sub.REF1 applied to the gates of transistors 20, 21, respectively, so as to provide a substantially constant voltage swing across the resistors R.sub.L1, R.sub.L2, during operation of the differential pair of transistors 22, 24 and the differential pair of transistors 26, 28. Furthermore a reference voltage V.sub.REF2 may be needed which should have the capability of insuring that a constant current is provided through each of the respective resistors R.sub.C, operatively associated with the differential pair of transistors 26, 28.
Additionally, a reference voltage V.sub.REF3 is useful in the situation where the transistors 22, 24 make up single-ended input to a differential pair, i.e., the input to the gate of transistor 22 is varied above and below the input signal V.sub.REF3. Also, in certain situations, such as relating to the use of reference voltage V.sub.REF4, the reference voltage should be capable of sinking a large and varying current, due to the fact that it may be operatively coupled to a large number of differential pair transistors (only one of which is shown at 22, 24), to prevent the voltage on node 30 from rising more than a diode drop above V.sub.REF4.
Heretofore, attempts have been made to provide circuits which generate such reference voltages and currents in a way so that the reference voltages and currents are not significantly affected by temperature or power supply voltage fluctuations in order to meet the needs described. Such circuits have limitations in achieving these goals, and the difficulty in achieving such goals is increased when there is an attempt to implement the circuits in gallium arsenide technology. For example, in a reference voltage generator circuit using gallium arsenide technology, since threshold voltages for GaAs FETs are difficult to control, any reference voltage affected by the particular value of an FET threshold voltage will be difficult to control.